Consumers can interact with merchants to conduct various financial payment transactions. For example, with the proliferation of mobile computing devices (e.g., smart phones and tablet computers, etc.), development of various attachable hardware devices has increased to provide expanded functionality to such devices. One such example is an attachable magnetic card reader device, used for reading credit or debit card information to facilitate the receipt and processing of payments. Some of these reader devices can be physically and communicatively coupled to an associated mobile device using a standard 3.5 mm audio plug when inserted into the headphone port of the mobile device. Given the nature of these devices, it can be desirable to ensure that certain components, such as security subsystems and the like, are continually powered and active. However, the physical size and nature of these card reader devices may not allow for replacing, adjusting, or otherwise making modifications to the device's system components to ensure adequate backup power. As such, it is desirable to develop approaches to ensure continual power to certain device components.